The inverted V bottom hull form, commonly known as a sea sled, was invented by Albert Hickman. The original hull form consisted of a rectangular hull platform with an inverted V section at the bow, with the V section becoming continuously and progressively shallower toward the stern until disappearing or nearly disappearing at the transom. The Hickman hull form has been recognized as one of the most efficient non-stepped planing hull forms having the ability to carry as much as eighty pounds per horsepower at planing speeds. Inverted V hulls capture bow waves which are normally deflected outboard and away from the hull and redirects the wave under the hull. This volume of captured water allows the boat to rise further out of the water at planing speeds thereby reducing resistance and consuming less energy. Moreover, the captured wake is filled with air, and aerated water being less dense than solid water, cushions the hull during further impacts with oncoming waves, making the Hickman hull ideal for rough water use. Additionally, inverted V hulls, having parallel sides and deep chines, exhibit great directional stability. Still yet further, the draft of a Hickman hull is less than most conventional hull forms, making it useful in shallow waters. Lastly, the hull's generally rectangular platform resulting from the wide forward sections makes the boat stable at all operating speeds.
Despite the foregoing, inverted V hulls exhibit several undesirable characteristics which various design modifications have attempted to minimize. For example, long parallel chines act like runners on a sled thereby making turning the boat extremely difficult. Moreover, aerated water under the hull is directed towards the center of the hull and exits at the transom flowing directly into the propeller which causes the propeller to cavitate. Typically, boats turning at high speed bank, or heel, toward the inside of the turn, however boats using the Hickman hull remain flat or heel towards the outside of the turn. The foregoing is unsettling to the crew, and a higher center of gravity of the hull structure combined with the centrifugal force generated during the turn can capsize the boat. The lack of heel in a turn combined with the near vertical and straight fore and aft sides of a boat using this hull can cause a condition known as “tripping over the chine”, where during a sliding turn, the edge of the hull strikes a wave, the chine catches on the water and the boat trips over the chine, rapidly tipping or flipping the boat athwartships. Furthermore, the inverted V section greatly reduces the depth of the hull along the centerline of the boat amidships and forward thereby reducing the useable internal volume of the boat and raising the center of gravity of the hull.
Planing hulls are well known in the art of boat hull design. The vast majority of hull forms used in planing boats have sectional shapes that are either rectangular, V shaped, round shaped, or combinations thereof. Generally, hulls using these shapes have a common aspect, i.e., the keel is lower than the chine or turn of the bilge. The dimensional characteristics of the hull, e.g., displacement, deadrise, strake and chine placement, cross-sectional shape, and longitudinal curvature, vary greatly and can be combined in endless variations. These features affect the ride qualities, top speed, maneuverability and horsepower requirements of a vessel to achieve a planing speed.
Planing round or V bottom hull types possess several undesirable design traits. For example, there is a tendency to squat, i.e., the stern sinks and the bow rises, when transitioning from operating in a displacement mode (slow speed) to a planing mode (higher speed). In a displacement mode, the hull is buoyed up by the displaced volume of water equal to the volume of the immersed hull at rest. In a planing mode, the hull is lifted up by the hydrostatic forces generated by the hull striking the water at high speed, at some angle of attack, which in turn causes the hull to skim across the surface of the water. During this transitional speed, i.e., the changing between displacement and planing modes where the boat has to “climb” over its own bow wave, the boat is less stable, hard to steer, and forward visibility is often dangerously reduced. Another unfavorable characteristic is the tendency to generate a large bow wave which, when piercing oncoming waves and water, causes this wave to fly outboard and upward, and potentially landing on the boat. Still yet another problem is the direct relationship between ride quality and required horsepower, i.e., deeper sections and greater deadrise result in a softer ride but greatly increase the horsepower requirements. Yet another issue is the reduced stability of the boat while operating below planing speeds. Conventional hulls with moderate deadrise are unstable when beached and make approaching the shore difficult due to their deeper draft.
Known boat hull forms incorporate various stepped chines, stepped hull sections, tunnels and various shaped cavities all of which have abrupt changes in the surface contour and may have angular edges and corners, often sharp and whose included angle approach 90 degrees. Angular discontinuities in the hull surface require substantial structural bracing and reinforcement to keep the hull bottom from flexing and cracking at these transitions. When these features are employed the resulting hull is specifically optimized to operate at certain speeds since water does not like to flow into or across sharp edges, which typically creates turbulence and/or drag, unless traveling at high speeds and traveling in a precisely controlled direction. Water flow can only be predicted and controlled when a vessel is operating on a smooth body of water.
There are yet other hull forms used on planing powerboat hulls. Examples of these hulls include hulls that exhibit traits known in the industry as tri-hulls, tunnel hulls, catamarans, and hybrid hulls that combine some or all of these forms. Catamarans and various tunnel hulls have the greatest stability due to their displaced volume being in two hulls spaced apart and interconnected, and an applied heeling force results in the greatest shift in the center of buoyancy and the largest righting moment. They typically are very fast requiring less energy to power them; however, they are harder to steer, lack useable internal volume, can pound in a seaway, and often are more complicated to construct. Tri-hull boats became exceedingly popular in the 1970's due to their useable internal volume and great stability at plane or at rest. Such hulls incorporate a central main hull running the full length of the boat and sponsons or smaller hull like appendages outboard and fully integrated with the main hull, intended to capture the bow wave. As newer hybrid combinations of the alternative hull forms were discovered the tri-hull virtually disappeared due to its reputation for severe pounding in anything but smooth water as well as the increased power needed to propel the craft. For example, the increased form drag caused by the added drag of the tri-hulls' sponsons, in addition to its increased hull mass due to added surface area, requires more power to propel the craft.
Numerous attempts have been made to combine the features and characteristics of the various possible cross-sectional hull forms in order to optimize handling, ride, power requirements, useable volume, stability, and any of the aforementioned desirable traits of the various shapes. However, no hull design has successfully improved the power requirements, ride and handling characteristics of mono-hull designs as set forth herebelow in the detailed description of various embodiments of the present invention.
The various hull designs known in the art all possess some shortcomings that detract from the boating experience. For example, known V hull designs are incapable of using trapped air and contained bow waves to reduce slamming while also increasing efficiency. In fact, some hull designs force air towards the center of the hull, inwardly toward the propeller, thereby causing cavitation and steering issues. This, as well as other drawbacks of known hull designs, have presented a long felt need for a hull design that improves the boating experience, while maintaining safety, minimizing wakes, etc.